Benchmarking quantum devices beyond classical capabilities

TL;DR

This paper introduces a modified Quantum Volume benchmarking method that overcomes classical computational limits, enabling scalable evaluation of increasingly large quantum devices while preserving their universal computational capabilities.

Contribution

It proposes a new circuit ensemble for the Quantum Volume test that allows direct heavy-output subspace determination without exponential classical simulation.

Findings

The modified test scales beyond classical computational limits.

It maintains the ability to evaluate universal quantum computation.

The approach overcomes the scalability barrier of existing benchmarks.

Abstract

Rapid development of quantum computing technology has led to a wide variety of sophisticated quantum devices. Benchmarking these systems becomes crucial for understanding their capabilities and paving the way for future advancements. The Quantum Volume (QV) test is one of the most widely used benchmarks for evaluating quantum computer performance due to its architecture independence. However, as the number of qubits in a quantum device grows, the test faces a significant limitation. It requires determining the subspace of the most probable outcomes, a task that is typically performed via classical simulation of the quantum circuit and therefore incurs an exponential computational cost. In this work, we propose modifications to the QV test, by adopting a carefully restricted circuit ensemble generated from a gate set that remains universal for quantum computation, that allows for the direct determination of the heavy-output subspace. Crucially, the modified circuits remain capable of general quantum computation. This approach overcomes the scalability barrier of the Quantum Volume test beyond classical computational limits, while still probing the key features of universal quantum computing.